use crate::ciphertext::Ciphertext;
use crate::elem::{Elem, ElemCommon, ElemVecZnx};
use crate::keys::SecretKey;
use crate::parameters::Parameters;
use crate::plaintext::Plaintext;
use base2k::sampling::Sampling;
use base2k::{
    ZnxInfos, Module, Scalar, ScalarZnxDft, ScalarZnxDftOps, VecZnx, VecZnxBig, VecZnxBigOps, VecZnxDft, VecZnxDftOps, VecZnxOps, MatZnxDft,
    MatZnxDftOps,
};

use sampling::source::{Source, new_seed};

impl Parameters {
    pub fn encrypt_rlwe_sk_tmp_bytes(&self, log_q: usize) -> usize {
        encrypt_rlwe_sk_tmp_bytes(self.module(), self.log_base2k(), log_q)
    }
    pub fn encrypt_rlwe_sk(
        &self,
        ct: &mut Ciphertext<VecZnx>,
        pt: Option<&Plaintext>,
        sk: &ScalarZnxDft,
        source_xa: &mut Source,
        source_xe: &mut Source,
        tmp_bytes: &mut [u8],
    ) {
        encrypt_rlwe_sk(
            self.module(),
            &mut ct.0,
            pt.map(|pt| pt.at(0)),
            sk,
            source_xa,
            source_xe,
            self.xe(),
            tmp_bytes,
        )
    }
}

pub struct EncryptorSk {
    sk: ScalarZnxDft,
    source_xa: Source,
    source_xe: Source,
    initialized: bool,
    tmp_bytes: Vec<u8>,
}

impl EncryptorSk {
    pub fn new(params: &Parameters, sk: Option<&SecretKey>) -> Self {
        let mut sk_svp_ppol: ScalarZnxDft = params.module().new_svp_ppol();
        let mut initialized: bool = false;
        if let Some(sk) = sk {
            sk.prepare(params.module(), &mut sk_svp_ppol);
            initialized = true;
        }
        Self {
            sk: sk_svp_ppol,
            initialized,
            source_xa: Source::new(new_seed()),
            source_xe: Source::new(new_seed()),
            tmp_bytes: vec![0u8; params.encrypt_rlwe_sk_tmp_bytes(params.cols_qp())],
        }
    }

    pub fn set_sk(&mut self, module: &Module, sk: &SecretKey) {
        sk.prepare(module, &mut self.sk);
        self.initialized = true;
    }

    pub fn seed_source_xa(&mut self, seed: [u8; 32]) {
        self.source_xa = Source::new(seed)
    }

    pub fn seed_source_xe(&mut self, seed: [u8; 32]) {
        self.source_xe = Source::new(seed)
    }

    pub fn encrypt_rlwe_sk(&mut self, params: &Parameters, ct: &mut Ciphertext<VecZnx>, pt: Option<&Plaintext>) {
        assert!(
            self.initialized == true,
            "invalid call to [EncryptorSk.encrypt_rlwe_sk]: [EncryptorSk] has not been initialized with a [SecretKey]"
        );
        params.encrypt_rlwe_sk(
            ct,
            pt,
            &self.sk,
            &mut self.source_xa,
            &mut self.source_xe,
            &mut self.tmp_bytes,
        );
    }

    pub fn encrypt_rlwe_sk_core(
        &self,
        params: &Parameters,
        ct: &mut Ciphertext<VecZnx>,
        pt: Option<&Plaintext>,
        source_xa: &mut Source,
        source_xe: &mut Source,
        tmp_bytes: &mut [u8],
    ) {
        assert!(
            self.initialized == true,
            "invalid call to [EncryptorSk.encrypt_rlwe_sk]: [EncryptorSk] has not been initialized with a [SecretKey]"
        );
        params.encrypt_rlwe_sk(ct, pt, &self.sk, source_xa, source_xe, tmp_bytes);
    }
}

pub fn encrypt_rlwe_sk_tmp_bytes(module: &Module, log_base2k: usize, log_q: usize) -> usize {
    module.bytes_of_vec_znx_dft(1, (log_q + log_base2k - 1) / log_base2k) + module.vec_znx_big_normalize_tmp_bytes()
}
pub fn encrypt_rlwe_sk(
    module: &Module,
    ct: &mut Elem<VecZnx>,
    pt: Option<&VecZnx>,
    sk: &ScalarZnxDft,
    source_xa: &mut Source,
    source_xe: &mut Source,
    sigma: f64,
    tmp_bytes: &mut [u8],
) {
    encrypt_rlwe_sk_core::<0>(module, ct, pt, sk, source_xa, source_xe, sigma, tmp_bytes)
}

fn encrypt_rlwe_sk_core<const PT_POS: u8>(
    module: &Module,
    ct: &mut Elem<VecZnx>,
    pt: Option<&VecZnx>,
    sk: &ScalarZnxDft,
    source_xa: &mut Source,
    source_xe: &mut Source,
    sigma: f64,
    tmp_bytes: &mut [u8],
) {
    let cols: usize = ct.cols();
    let log_base2k: usize = ct.log_base2k();
    let log_q: usize = ct.log_q();

    assert!(
        tmp_bytes.len() >= encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q),
        "invalid tmp_bytes: tmp_bytes={} < encrypt_rlwe_sk_tmp_bytes={}",
        tmp_bytes.len(),
        encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q)
    );

    let log_q: usize = ct.log_q();
    let log_base2k: usize = ct.log_base2k();
    let c1: &mut VecZnx = ct.at_mut(1);

    // c1 <- Z_{2^prec}[X]/(X^{N}+1)
    module.fill_uniform(log_base2k, c1, cols, source_xa);

    let (tmp_bytes_vec_znx_dft, tmp_bytes_normalize) = tmp_bytes.split_at_mut(module.bytes_of_vec_znx_dft(1, cols));

    // Scratch space for DFT values
    let mut buf_dft: VecZnxDft = VecZnxDft::from_bytes_borrow(module, 1, cols, tmp_bytes_vec_znx_dft);

    // Applies buf_dft <- DFT(s) * DFT(c1)
    module.svp_apply_dft(&mut buf_dft, sk, c1);

    // Alias scratch space
    let mut buf_big: VecZnxBig = buf_dft.as_vec_znx_big();

    // buf_big = s x c1
    module.vec_znx_idft_tmp_a(&mut buf_big, &mut buf_dft);

    match PT_POS {
        // c0 <- -s x c1 + m
        0 => {
            let c0: &mut VecZnx = ct.at_mut(0);
            if let Some(pt) = pt {
                module.vec_znx_big_sub_small_a_inplace(&mut buf_big, pt);
                module.vec_znx_big_normalize(log_base2k, c0, &buf_big, tmp_bytes_normalize);
            } else {
                module.vec_znx_big_normalize(log_base2k, c0, &buf_big, tmp_bytes_normalize);
                module.vec_znx_negate_inplace(c0);
            }
        }
        // c1 <- c1 + m
        1 => {
            if let Some(pt) = pt {
                module.vec_znx_add_inplace(c1, pt);
                c1.normalize(log_base2k, tmp_bytes_normalize);
            }
            let c0: &mut VecZnx = ct.at_mut(0);
            module.vec_znx_big_normalize(log_base2k, c0, &buf_big, tmp_bytes_normalize);
            module.vec_znx_negate_inplace(c0);
        }
        _ => panic!("PT_POS must be 1 or 2"),
    }

    // c0 <- -s x c1 + m + e
    module.add_normal(
        log_base2k,
        ct.at_mut(0),
        log_q,
        source_xe,
        sigma,
        (sigma * 6.0).ceil(),
    );
}

impl Parameters {
    pub fn encrypt_grlwe_sk_tmp_bytes(&self, rows: usize, log_q: usize) -> usize {
        encrypt_grlwe_sk_tmp_bytes(self.module(), self.log_base2k(), rows, log_q)
    }
}

pub fn encrypt_grlwe_sk_tmp_bytes(module: &Module, log_base2k: usize, rows: usize, log_q: usize) -> usize {
    let cols = (log_q + log_base2k - 1) / log_base2k;
    Elem::<VecZnx>::bytes_of(module, log_base2k, log_q, 2)
        + Plaintext::bytes_of(module, log_base2k, log_q)
        + encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q)
        + module.vmp_prepare_tmp_bytes(rows, cols)
}

pub fn encrypt_grlwe_sk(
    module: &Module,
    ct: &mut Ciphertext<MatZnxDft>,
    m: &Scalar,
    sk: &ScalarZnxDft,
    source_xa: &mut Source,
    source_xe: &mut Source,
    sigma: f64,
    tmp_bytes: &mut [u8],
) {
    let log_q: usize = ct.log_q();
    let log_base2k: usize = ct.log_base2k();
    let (left, right) = ct.0.value.split_at_mut(1);
    encrypt_grlwe_sk_core::<0>(
        module,
        log_base2k,
        [&mut left[0], &mut right[0]],
        log_q,
        m,
        sk,
        source_xa,
        source_xe,
        sigma,
        tmp_bytes,
    )
}

impl Parameters {
    pub fn encrypt_rgsw_sk_tmp_bytes(&self, rows: usize, log_q: usize) -> usize {
        encrypt_rgsw_sk_tmp_bytes(self.module(), self.log_base2k(), rows, log_q)
    }
}

pub fn encrypt_rgsw_sk_tmp_bytes(module: &Module, log_base2k: usize, rows: usize, log_q: usize) -> usize {
    let cols = (log_q + log_base2k - 1) / log_base2k;
    Elem::<VecZnx>::bytes_of(module, log_base2k, log_q, 2)
        + Plaintext::bytes_of(module, log_base2k, log_q)
        + encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q)
        + module.vmp_prepare_tmp_bytes(rows, cols)
}

pub fn encrypt_rgsw_sk(
    module: &Module,
    ct: &mut Ciphertext<MatZnxDft>,
    m: &Scalar,
    sk: &ScalarZnxDft,
    source_xa: &mut Source,
    source_xe: &mut Source,
    sigma: f64,
    tmp_bytes: &mut [u8],
) {
    let log_q: usize = ct.log_q();
    let log_base2k: usize = ct.log_base2k();

    let (left, right) = ct.0.value.split_at_mut(2);
    let (ll, lr) = left.split_at_mut(1);
    let (rl, rr) = right.split_at_mut(1);

    encrypt_grlwe_sk_core::<0>(
        module,
        log_base2k,
        [&mut ll[0], &mut lr[0]],
        log_q,
        m,
        sk,
        source_xa,
        source_xe,
        sigma,
        tmp_bytes,
    );
    encrypt_grlwe_sk_core::<1>(
        module,
        log_base2k,
        [&mut rl[0], &mut rr[0]],
        log_q,
        m,
        sk,
        source_xa,
        source_xe,
        sigma,
        tmp_bytes,
    );
}

fn encrypt_grlwe_sk_core<const PT_POS: u8>(
    module: &Module,
    log_base2k: usize,
    mut ct: [&mut MatZnxDft; 2],
    log_q: usize,
    m: &Scalar,
    sk: &ScalarZnxDft,
    source_xa: &mut Source,
    source_xe: &mut Source,
    sigma: f64,
    tmp_bytes: &mut [u8],
) {
    let rows: usize = ct[0].rows();

    let min_tmp_bytes_len = encrypt_grlwe_sk_tmp_bytes(module, log_base2k, rows, log_q);

    assert!(
        tmp_bytes.len() >= min_tmp_bytes_len,
        "invalid tmp_bytes: tmp_bytes.len()={} < encrypt_grlwe_sk_tmp_bytes={}",
        tmp_bytes.len(),
        min_tmp_bytes_len
    );

    let bytes_of_elem: usize = Elem::<VecZnx>::bytes_of(module, log_base2k, log_q, 2);
    let bytes_of_pt: usize = Plaintext::bytes_of(module, log_base2k, log_q);
    let bytes_of_enc_sk: usize = encrypt_rlwe_sk_tmp_bytes(module, log_base2k, log_q);

    let (tmp_bytes_pt, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_pt);
    let (tmp_bytes_enc_sk, tmp_bytes) = tmp_bytes.split_at_mut(bytes_of_enc_sk);
    let (tmp_bytes_elem, tmp_bytes_vmp_prepare_row) = tmp_bytes.split_at_mut(bytes_of_elem);

    let mut tmp_elem: Elem<VecZnx> = Elem::<VecZnx>::from_bytes_borrow(module, log_base2k, log_q, 2, tmp_bytes_elem);
    let mut tmp_pt: Plaintext = Plaintext::from_bytes_borrow(module, log_base2k, log_q, tmp_bytes_pt);

    (0..rows).for_each(|row_i| {
        // Sets the i-th row of the RLWE sample to m (i.e. m * 2^{-log_base2k*i})
        tmp_pt.at_mut(0).at_mut(row_i).copy_from_slice(&m.raw());

        // Encrypts RLWE(m * 2^{-log_base2k*i})
        encrypt_rlwe_sk_core::<PT_POS>(
            module,
            &mut tmp_elem,
            Some(tmp_pt.at(0)),
            sk,
            source_xa,
            source_xe,
            sigma,
            tmp_bytes_enc_sk,
        );

        // Zeroes the ith-row of tmp_pt
        tmp_pt.at_mut(0).at_mut(row_i).fill(0);

        // GRLWE[row_i][0||1] = [-as + m * 2^{-i*log_base2k} + e*2^{-log_q} || a]
        module.vmp_prepare_row(
            ct[0],
            tmp_elem.at(0).raw(),
            row_i,
            tmp_bytes_vmp_prepare_row,
        );
        module.vmp_prepare_row(
            &mut ct[1],
            tmp_elem.at(1).raw(),
            row_i,
            tmp_bytes_vmp_prepare_row,
        );
    });
}